Under the heavy metals program, the Bureau of Mines conducted investigations at the Old Badger Hill placer mine in Nevada County, California, to collect data regarding drilling and sampling methods and deposit characteristics. A team of five Bureau research groups studied ways to develop new or improved placer mining technology in the Tertiary gold-bearing channel gravel of northern California. This report describes the techniques used and the results obtained in the sampling and drilling stage of deposit delineation studies that were conducted. Sampling included the collection and processing of 400 tons of large- and small-volume samples from drill holes, underground workings, surface pits, and blast hole rounds. A total of 355 samples averaging 2,296 pounds per sample provided reasonably accurate data for analysis of the gold distribution. These studies indicate that the bulk of the gold is within 40 feet of bedrock in stacked, lenticular zones of cemented gravel largely confirmed to the relatively narrow, meandering course of the deepest portion of the bedrock channel.